Project description:Comparative metabolomics study of fungal foliar endophytes and their long-lived host, the Rainforest palm Astrocaryum sciophilum: a model for deciphering host-microbe interactions and exploring metabolite chemodiversity.
Project description:Sclerotinia sclerotiorum, the causal agent of white mould, is a necrotrophic fungal pathogen responsible for extensive crop loss. Current control options rely heavily on the application of chemical fungicides that are becoming less effective and may lead to the development of fungal resistance. In the current study, we used a foliar spray application of boron to protect Brassica napus (canola) from S. sclerotiorum infection using whole plant infection assays. Application of boron to aerial surfaces of the canola plant reduced the number of S. sclerotiorum forming lesions by 87% compared to an untreated control. We used dual RNA sequencing to profile the effect of boron on both the host plant and fungal pathogen during the infection process. Differential gene expression analysis and gene ontology term enrichment further revealed the mode of action of a foliar boron spray at the mRNA level. A single foliar application of boron primed the plant defense response through the induction of genes associated with systemic acquired resistance while an application of boron followed by S. sclerotiorum infection induced genes associated with defense-response-related cellular signalling cascades. Additionally, in S. sclerotiorum inoculated on boron-treated B. napus, we uncovered gene activity in response to salicylic acid breakdown, consistent with salicylic-acid-dependent systemic acquired resistance induction within the host plant. Taken together, this study demonstrates that a foliar application of boron results in priming of the B. napus plant defense response, likely through systemic acquired resistance, thereby contributing to increased tolerance to S. sclerotiorum infection.
Project description:The endophytic fungi of certain grasses and herbaceous plants provide anti-herbivore defense compounds, thus living in mutualistic interaction with their hosts. Still, there is little information on such cooperation for tree-associated endophytes. We investigate the influence of the endophytic fungus Cladosporium cladosporioides on the chemical defenses of black poplar Populus nigra trees and the consequences on feeding preference, fitness of herbivorous insects, and insect community assembly. Strikingly, endophyte colonization increases both constitutive- and induced poplar defenses. Generalist Lymantria dispar larvae prefer and perform better on uninfected poplars due to the higher concentrations of salicinoids and fungal alkaloid stachydrine in endophyte-infected leaves. Under field conditions, the endophytic fungus shapes insect community assembly in young black poplar trees. Our results show that endophytic fungi can play a significant role in defending trees against herbivorous insects and structuring insect communities.
Project description:Comparative metabolomics study of fungal foliar endophytes and their long-lived host, the Rainforest palm Astrocaryum sciophilum: a model for deciphering host-microbe interactions and exploring metabolite chemodiversity.
Project description:The “Amoeboid Predator-Fungal Animal Virulence Hypothesis” posits that interactions with environmental phagocytes shape the evolution of virulence traits in fungal pathogens. In this hypothesis, selection to avoid predation by amoeba inadvertently selects for traits that contribute to fungal escape from phagocytic immune cells. Here, we investigate this hypothesis in the human fungalpathogens Cryptococcus neoformans and Cryptococcus deneoformans. Applying quantitative trait locus (QTL) mapping and comparative genomics, we discovered a cross-species QTL region that is responsible for variation in resistance to amoeba predation. In C. neoformans, this same QTL was found to have pleiotropic effects on melanization, an established virulence factor. Through fine mapping and population genomic comparisons, we identified the gene encoding the transcription factor BZP4 that underlies this pleiotropic QTL and we show that decreased expression of this gene reduces melanization and increases susceptibility to amoeba predation. Despite the joint effects of BZP4 on amoeba resistance and melanin production, we find no relationship between BZP4 genotype and escape from macrophages or virulence in murine models of disease. Our findings provide new perspectives on how microbial ecology shapes the genetic architecture of fungal virulence, and suggests the need for more nuanced models for the evolution of pathogenesis that account for the complexities of both microbe-microbe and microbe-host interactions.
Project description:The transcriptome of Melampsora larici-populina was analysed in telia (in planta sample, early telia harvested before overwintering), uredinia (in planta sample, 168 hours post-inoculation, hpi), in planta during biotrophic growth (96 hpi) and in resting urediniospores. The array probes were designed from gene models taken from the Joint Genome Institute (JGI, Department of Energy) Melampsora larici-populina genome sequence version 1. The aim of this study was to determine gene expression in early telia formed in decaying poplar leaves in autumn before the overwintering process and to compare this expression with other stages of the poplar rust life cycle that were previously described (i.e., resting urediniospores as pure fungal material, and uredinia and biotrophic growth stage as poplar leaf infecting fungal structures). This study should highlight telia-specific transcripts and contribute to the understanding of the poplar rust biological cycle.
Project description:Magnaporthe oryzae causes rice blast, the most devastating foliar fungal disease of cultivated rice. During disease development the fungus simultaneously maintains both biotrophic and necrotrophic growth corresponding to a hemi-biotrophic life style. The ability of M. oryzae to also colonize roots and subsequently develop blast symptoms on aerial tissue has been recognized. The fungal root infection strategy and the respective host responses are currently unknown. Global temporal expression analysis suggested a purely biotrophic infection process reflected by the rapid induction of defense response-associated genes at the early stage of root invasion and subsequent repression coinciding with the onset of intracellular fungal growth. The same group of down-regulated defense genes was increasingly induced upon leaf infection by M. oryzae where symptom development occurs shortly post tissue penetration. Our molecular analysis therefore demonstrates the existence of fundamentally different tissue-specific fungal infection strategies and provides the basis for enhancing our understanding of the pathogen life style.
Project description:We revealed that a rhamnolipid protects wheat against the hemibiotrophic fungal pathogen Zymoseptoria tritici. Foliar application of the biomolecule primes, during the early stages of infection, the expression of genes associated with different functional groups of genes.